Livestock confinement facilities generate large amounts of animal waste that can create serious environmental and human health concerns. For example, animal waste constituents such as organic matter, nitrogen, phosphorus, pathogens and metals can degrade water quality, air quality, and adversely impact human health. Organic matter, for example, contains a high amount of biodegradable organics and when discharged to surface waters will compete for, and deplete the limited amount of dissolved oxygen available, causing fish kills and other undesirable impacts. Similarly nutrient loading from nitrogen and phosphorus can lead to eutrophication of surface waters.
The annual accumulation of organic waste in the world is immense. There are approximately 450,000 Animal Feeding Operations (“AFOs”) in the United States. Common types of AFOs include dairies, cattle feedlots, and poultry farms. A single dairy cow produces approximately 120 pounds of wet manure per day. The waste produced per day by one dairy cow is equal to that of 20-40 people. If properly stored and used, manure from animal feeding operations can be a valuable resource.
Anaerobic digesters can be used to process waste fibrous material, such as wood and manure, and convert the material into biogas composed of methane, ammonia, and CO2, and remaining fibrous residuals. The biogas, primarily methane, can be used to produce electricity. The remaining residual fibrous material has been used for cow bedding, land nutrient amendment, or as compost. Large dairies have an abundance of this remaining fibrous material and managers of these dairies would like to have a value-added outlet other than bedding or land application.
Others have experimented with digester solids to determine what type of products could be made from the material; however, to date, methods used to convert fibrous material into other products have been limited. Most experiments have focused on drying the residual material, then combining it with adhesive, and possibly wood, to make an air-laid dry-formed composite board. Others have combined the residual material with plastic to extrude it into various outdoor products. However, these products have been limited in size, shape, strength, utility and industrial applicability.
Therefore, methods that can convert the fibrous residual material into a product of value, such as a composite component, would be extremely useful.